^ New rotors are not going to stay rust free for long. Rotors get surface rust and abrade it off with a few uses. Every time you wash the car and let it sit, for example. The first time you touch the brakes they can sound pretty harsh, in that situation. Then a block or two and they're ok. I wouldn't change rotors unless: 1. They're nearing minimum thickness. 2. They've cracked (usually in concert with above). 3. They've warped. 4. The car has sat idle an inordinately long time, to where it's not surface rust any more. Some here have suggested occasionally shifting into Neutral to help exercise the friction brakes. I'm not sure that's even needed, the brakes are constantly in touch with the disk, and employed at least a bit in every stop. The example of the car having been washed and sat for a day or so: I've heard terrific noise at first use, and you can tell from the sound every time the friction brakes come into play. And the sound dissipates in a few blocks.
I have owned a G2, and passed it on to my daughter when she went to college. She got hit by a person who blew through a stop sign at 164k to end its life. Car never got new pads or rotors in the 12+ years we owned it. Believe me, I tried convincing my regular mechanics to do it, but they would not do it as they said they were fine and didn't want to waste my money. So I just changed the brake fluid every 3 years or so. I've not had an issue with rusty rotors on either that Prius or my v. What's more, as I've become something of a bike commuter, my v sits a lot. So did the G2 for that matter when it was at college. I don't know what to tell you other than I really don't think replacing rotors more often than pads makes a whole lot of sense. I'd never do it, but I'm not going to tell someone else not to do what makes them feel comfortable either.
nsfbr. My original post way back did hint that those who live in a region where they salt the roads are salted in the winter need to replace the rotors more often than those who dont. And those who live in a desert climate may never need their rotors replaced. And if you slam your brake pedal every time you need to stop you're using your friction brakes more than you should. Great for prolonging rotor life but bad for fuel economy
I live in an area where salt on the road is the norm in the winter. I don't slam on my brakes, which is why I've never replaced so much as a pad and I assure you my mileage does not reflect overuse of the physical brakes. I remain skeptical, but I'm also going to admit that my experience does not define the universe of possible experiences.